Feline ventral abdominal wall angiosarcoma: haemangiosarcoma or lymphangiosarcoma? Clinical and pathological characteristics in nine cases.

Objectives: Angiosarcomas are rare malignant mesenchymal neoplasms of endothelial cell origin with a predilection to the ventral abdominal wall in cats. Larger case series describing this entity are lacking.
Methods: Two referral centre laboratory databases were searched for angiosarcoma of the ventral abdominal wall. Nine cases with a histological diagnosis were included. Immunohistochemistry (factor VIII and PROX-1 antibodies) was used to phenotype them as haemangiosarcoma or lymphangiosarcoma.
Results: All cats presented with a ventral abdominal mass, five of which were producing a serosanguinous discharge. Eight underwent tumour staging and pulmonary metastases were suspected in one cat (but not histologically confirmed). With histopathology alone, a diagnosis of angiosarcoma and lymphangiosarcoma was made in four and five cases, respectively. After immunohistochemistry, five cases had a haemangiosarcoma phenotype and four had a lymphangiosarcoma phenotype, including two cases of lymphangiosarcoma that were reclassified as hemangiosarcoma. Eight cats received treatment (either surgery with or without adjuvant therapies or medical management alone). Six cats were euthanased due to local disease progression. The median survival time for haemangiosarcoma was 166 days (range 137-381), and for lymphangiosarcoma it was 197 days (range 67-208). Two cats with haemangiosarcoma remained alive for a follow-up period of 329 and 580 days, respectively.
Conclusions and Relevance: Feline ventral abdominal angiosarcomas are rare locally aggressive neoplasms. While histology often provides a diagnosis of angiosarcoma, immunohistochemistry is ultimately required to differentiate between haemangiosarcoma and lymphangiosarcoma phenotypes. Further studies are required to evaluate whether the different phenotypes have an impact on treatment response and outcome.
Competing Interests: Conflict of interestThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.